美洲鲥繁殖特性研究

Reproductive Property of the American Shad, Alosa sapidissima, under Reared Conditions

摘要: 采用组织学、形态学及数量统计学等分析方法，研究了自2015年10月至2016年9月人工养殖条件下美洲鲥亲鱼繁殖周年特性。结果表明，美洲鲥卵巢发育分为6期，精巢发育分为6期；根据卵母细胞的形态结构、卵黄物质积累和滤泡细胞的变化，将卵子发生划分为6个时相；根据精母细胞的形态结构及变化，将精子发生分为6期；不同发育阶段的卵巢中至少含有两种处于不同发育时相的卵母细胞，且卵径分布呈现明显的“双峰型”也表明美洲鲥产卵类型为部分同步类型。在性腺周期发育过程中，雌雄亲鱼性腺指数(GSI)在4~6月份保持较高的水平，且最高值均出现在5月(雌鱼：29.24% ± 3.84%，雄鱼：8.06% ± 1.19%)，暗示了美洲鲥繁殖季节主要发生在4~6月份。自2016年1月到3月，雌鱼肝体比(HIS)迅速增加，且在3月到达最大值(2.05% ± 0.05%)。而雄鱼自2016年1月到6月，指数快速降低，在6月到达最低值(0.93% ± 0.1%)，说明了肝脏在性腺发育过程中发挥着重要的生理作用。肥满度(CF)在繁殖盛期达到最大，表现出与GSI类似的变化趋势。美洲鲥绝对繁殖力为69,033.99粒~414,184.28粒(平均304,251.71 ± 61,293.27)，相对繁殖力为71.38粒/g~395.38粒/g (平均254.44 ± 49.11粒/g)。综上所述，美洲鲥产卵类型属于非同步批次产卵类型，繁殖期主要为4~6月，其繁殖力低，繁殖期较长。

Abstract: In order to assess the reproductive property of American shad Alosa sapidissima in the reproductive cycle, the biological indexes, oocyte development, the patterns of oogenesis, spawning season and fecundity were studied by applying histologic technology, ecology and quantitative trait method. The result showed that the development of ovary and testis was divided into six stages, respectively; in addition, the oogenesis and spermatogenesis could be divided into six phases, respectively; at least two distinct batches of vitellogenic oocytes were found in American shad ovaries at different development stage, and in mature ovaries, there were two additional modes of oocytes present, indicating that this species is a group synchronized multiple batch spawners. During the gonadal development, the mean GSI for females and males remained a high level from April to June for 2016, and a maximum was reached in May (29.24% ± 3.84% for female and 8.06% ± 1.19% for male), suggesting that the reproduction periods occurred from April to June. The HIS of females displayed a sharp increase was observed from January to March, with peak values occurring in March (2.05% ± 0.05%). The HIS of males exhibited a fast fall from January to June, and the lowest in June (0.93% ± 0.1%). The estimated values of batch fecundity varied widely from 69,033.99 to 414,184.28 eggs per fish (mean = 304,251.71 ± 61,293.27). The relative batch fecundity ranged from 71.38 to 395.38 oocytes g−1 body weight (mean = 254.44 ± 49.11). In a word, American shad belongs to the non-synchronized multiple batch spawner, and the breeding season is from April to June. Its fecundity is low and the breeding period is long.